Information display device

ABSTRACT

Information display apparatus includes an opaque member having a two-dimensional array of light-transmissive areas arranged in rows and columns. Each area has an individual shutter pivoted for movement between positions in which it has different effects upon light passing through the area by a magnetic actuator member coupled with the shutter. Magnetic field producing means in a first set each produce fields limited to all the actuators of a row while those of a second set each produce fields limited to actuators of a column. Predetermined changes in electric currents applied to the row and column field producing means uniquely associated with an actuator will produce reversal of the shutter position. The actuators may be soft-iron or permanent magnets. The field producing means for a row may either enable or inhibit actuator movement when energized.

United States Patent 1 Salam 51 Dec. 4, 1973 INFORMATION DISPLAY DEVICE [75] Inventor: Hassan Paddy Abdel Salam, Primary Exammer*wm' Gneb London, England AttrneyLawrence E. Laubscher et al.

[73] Assignee: Universal Telewriters (Pty) Limited, 57 ABSTRACT D urban Rgpubhc of fiw Information display apparatus includes an opaque [22] Filed: Apr. 14, 1972 member having a two-dimensional array of light- Foreign Application Priority Data transmissive areas arranged in rows and columns.

I Each area has an individual shutter pivoted for movement between positions in which it has different ef- [30] fects upon light passing through the area by a mag- Apr. 14, 1971 Great Britain 9,406/71 I netic actuamr member couPled with the Shutter- 7 netic field producing means in a first set each produce [52] CL 40/2 C, 40/52 R 340/336 fields limited to all the actuators of a row while those 51 int. Cl. 609i 9/30- of a Second Set each Produce fields limited to actua- [58] Field of Search 40/28 0, 52 R, 52 A, o of a columnpredetermined changes in electric 40/52 340/336 f currents applied to the row and column field producing means uniquely associated with an actuator will [56] References Cited produce reversal of the shutter position. The actuators UNITED STATES PATENTS may be soft-iron or permanent magnets. The field producing means for a row may either enable or inhibit I: actuator movement when energized- 3:O36:300 /1962 Knight 340/336 x 9 Claims, 10 Drawing Figures 21 23\ 25 41 C I C 44 67 v I 22 9/ 24,26 '26\* 42 C I 5 C \A g A o L 5 0 TATENTEUUEC 41975 3.775881 SHEET 20? 3 INFORMATION DISPLAY DEVICE BACKGROUND OF THE INVENTION Information display apparatus including a .twodimensional array of selectively operable indicator devices is described in U.S. Pat. No. 3,562,938 issued to the assignee of the instant application.

A display apparatus described in United Kingdom Pat. Specification No. 941,696 includes an array of contiguous cells each having therein a shutter member movable to modify the light passing through the cell in response to simultaneous energization of two conductors producing mutually aiding magnetic fields in the same alinement. The currents pass through conductors fixed upon the shutter members themselves and the fields produce cooperate with those of fixed permanent magnets, resulting in a complex and consequently expensive device.

This apparatus includes a two-dimensional array of shutter members moved from one to another of two stable positions by forces generated directly in the shutter members themselves in response to energiz ation by a electric current of a selected conductor of one set of coordinate conductors and of a selected conductor of one of two sets of conductors associated with the other coordinate direction in accordance with the required direction of movement of the shutter member. It is a disadvantage of such apparatus that two different setsof conductors are required for moving the shutter members in opposite directions. This necessitates substantial obstruction of the available illuminated area of the display.

SUMMARY OF THE INVENTION An information display device in accordance with the invention includes a planar opaque member having therein a two-dimensional array of light-transmissive areas arranged in a two-dimensional array of rows and columns. Each light-transmissive area has an associated shutter member pivotally mounted for movement between two stable positions in which it has different effects upon light passing through the area. Each shutter member is coupled for actuation between its stable positions by a respective actuator member of magnetic material. Each one of a first system of magnetic field producing means produces in response to an energizing current a first magnetic field having a first alinement and being confined to the actuator members of a row. Each one of a second system of magnetic field producing means produces in response to an energizing current a second magnetic field having a second alinement and being confined to the actuator members of a column. Each shutter member is movable between its stable positions in response to forces produced on the actuator member as a result of predetermined changes in the magnetic fields produced by the field producing means of said first and of said second system of which the fields are uniquely associatedwith that actuator member. I

Preferred features and advantagesof embodiments of the invention will become apparent from the following description taken in conjunction with the accompanying drawing, of which:

FIG. I is a schematic perspective view of one embodiment of information display array;

FIGS. 2 and 3 illustrate the operation of an embodiment of shutter device which may be used in the embodiment of FIG. 1',

FIG. 4 is a perspective representation of one shutter arrangement of an alternative embodiment of the invention;

FIG. 5 is a cross-sectional view of the shutter arrangement of FIG. 4;

FIG. 5A is a detailed section showing a modification of the arrangement of FIG. 5;

FIG. 6 is a cross-sectional view of one shutter arrangement of a further embodiment of the invention;

FIG. 7 is a plan view of the shutter arrangement shown in FIG. 6;

FIG. 8 is a schematic diagram illustrating one arrangement for selectively energizing the conductors of an embodiment of the invention; and

FIG. 9 is a schematic diagram illustrating one arrangement for selectively changing the currents in the conductors of another embodiment of the invention.

In the following description the terms vertical and horizontal are used to denote elements extending in those directions when a display device in accordance with the invention including an array of light transmissive areas arranged in an array of rectangular coordinates is disposed with the plane of the array vertical and the rows and columns of apertures respectively horizontal and vertical. These terms are not to be construed as con-stituting a limitation upon the disposition of the apparatus when in use. I

The display device illustrated in FIG. I is of much smaller extent than would normally be required, in that it includes only six selectively exposed and occulted apertures. However, it will be apparent that the principle described in relation to FIG. 1 may be equally well applied to arrays including far greater numbers of apertures.

The device 1 shown in FIG. 1 comprises an opaque laminar member 2 pierced by apertures equi-spaced in a two-dimensional array. Three only of the apretures are visible, at 4, 5 and'6, while three more are hidden by shutters, as will be described. With each aperture is associated a respective one of shutter members 1 1, l2, l3, 14, 15 and 16. In the present embodiment each of these shuttermemb'ers is carried on the upper end of a respective permanent magnet 21, 22, 23, 24, 25,26 which is pivoted to opaque member 2 at its lower end for movement in a plane parallel to that of member 2. In each case the like poles of the permanent magnets are uppermost. Suitable stops (not shown) limit the movements of the magnets between respective gravitationally stable positions in which the attached shutter member respectively exposes or occults a respective aperture. 7

Co-operating with the permanent magnets 21 26 are five electrical conductor members 31, 32, 33 and 41, 42. Conductors 31, 32, 33 are disposed in respective vertical planes perpendicular to opaque member 2 and advantageously including the respective pivot axes of magnets 21 26 so as to form single-turn windings embracing the respective magnets, while conductors 41 and 42 lie in respective horizontal planes, again so as to form single-turn windings embracing the magnets. It will be seen that these windings are such as to generate orthogonally disposed magnetic fields. These windings are shown for convenience in illustration as embracing the pivot ends of the magnets but may be raised from this position as may be convenient. When a current of appropriate polarity is passed through one of horizontal conductors 41, 42 its effect is either to tend to raise the free (unpivoted) end of the associated permanent magnets, or to urge them downwards. A current of appropriate direction passed through a vertical conductor 31, 32 or 33 will tend to move the free ends of the associated magnets to the left or to the right as may be required. A pulse of current of appropriate direction and duration passed through any one of vertical conductors 31 33 can therefore be used to move any magnet associated with that conductor to the left or to the right, providing that its movement is not impeded by a current passed through the associated horizontal conductor and tending to hold the magnet in its'present position. An alternative method of operation is to arrange that the values of the currents V which are passed through the vertical conductors are insufficient to produce movement of a magnet unless the associated horizontal conductor carries a current which is tending to raise the magnet, thus assisting the switching action.

It should be understood that conductors 31 33 each surround the whole array of shutter control arrangments, each conductor being common to all the shutters in a row or in a column.

FIGS. 2 and 3 illustrate the two stable positions of a shutter element of the arrangement described in relation to FIG. 1. A permanent magnet 21 is pivoted at 21a for movement in a plane parallel to that of opaque member 2 in which is the aperture 4 to be occulted and exposed by a shutter 11 secured to magnet 21. One limb of vertical conductor 31 is advantageously adhesively secured to the surface of opaque member 2, as

is one limb of horizontal conductor 41. The other limb may be similarly secured to a further insulating substrate (not shown) disposed parallel to member 2 and in front of it as seen in FIGS. 2 and 3. These conductor limbs may be conductors adhesively secured to opposite faces of opaque member 2, or both may be secured to the same face, in which'case appropriate insulation must be provided between them at their crossing point. The remaining limbs of the horizontal and vertical conductors may be similarly adhesively secured to another similarly apertured opaque member, or to a transparent member.'Altematively, the-vertical and horizontal conductors may be carried upon flexible transparent or appropriately apertured members which are bent to form the conductor loops and placed around the apertured opaque member and the magnets so as to position the conductors in appropriate relation to the magnets.

A convenient manner of providing the appropriate arrays of row and column conductors is to employ laminar conductors formed on an initially planar flexible substrate which may then be folded or wrapped about the switching array with the conductors aligned with the rows or with the columns of the array. Either oneturn or multitum conductors may thus be provided on an initially planar substrate.

The movement of shutter 11 is limited to stop pins 18, 19. These may be of ferromagnetic material to improve the stability of the shutter in its limiting positions. The combination of magnet and shutter member secured together which is described above may be replaced by a unitary member of appropriate material and form.

FIGS. 4 and 5 illustrate an alternative embodiment of the invention in which the actuator differs from that described above. An opaque laminar member 2 is pierced by a two-dimensional array of apertures of which one only is shown at 4. This aperture is alternatively exposed or occulted by a shutter member 1 I mounted on the upper end of a member 60 of soft-iron or other magnetic material of low coercive force and low relentivity which is pivoted at 62 for movement in a plane parallel to that of opaque apertured member 2. Movement of member 60 and shutter 11 is limited by stop pins 63, 63 projecting from member 2, or in some other manner if more convenient. Stop pins 63, 63 may be formed as small permanent magnets to assist the stability of the actuator in its extreme positions. As before, electrical conductors 31 and 32 are used to produce the magnetic fields which control the shutter. In this case, however, the magnetic field used to excite member 60 is generated by a conductor 32 of which the two limbs lie in a common vertical plane. Between the limbs of conductor 32 extends a tubular soft-iron member 61, to the end of which is attached the lower end of shutter actuating member 60. Member 61 is pivotally mounted upon a pin 62 secured in member 2 so that shutter 11 and actuator member 60 may move in a plane parallel to member 2 and closely spaced therefrom. The passage of an electric current through conductors 32, 32' will generate a magnetic field of which the lines of force in the neighbourhood of member 61 are generally horizontal. This field will induce a corresponding state of magnetization in member 60. If now an electric current is also passed through conductor 31, the two limbs of which conveniently lie in a common vertical plane perpendicular to the plane of apertured member 2, a force will be exerted on member 60 which, if the two electric currents are of appropriate magnitude, will be sufficient to pivot member 60 and attached shutter 11 about pivot 62 to a position in which shutter 11 is arrested by stop pin 63' and the shutter is occulting aperture 4. Reversal of either the current in conductor 31 or the current in conductor 32 will produce a reversely directed force on member 60 to return the shutter 11 to its initial position abutting stop pin 63, as shown. Thus, as before, movement of a shutter is produced only when respective appropriately directed currents are passed through thetwo conductors uniquely associated with that shutter.

In the alternative arrangement illustrated by FIG. 5A a soft-iron member 61a is fixedly positioned upon a pivot pin 62a and an actuator member 60a is positioned upon pin 62a closely adjacent soft-iron member 61a but free to pivot about pin 62a. Otherwise, the construction and operations are as described for the embodiment of FIG. 5. Thus in FIG. 5A a fixed ferromagnetic member is positioned to increase the strength of the magnetic field produced by conductor 32. Other arrangements of fixed ferromagnetic members for augmenting the magnetic field strengths of both conductors will be apparent to those skilled in the art and will not be further described.

In the arrangement shown in FIGS. 6 and 7 there is again formed in the opaque member a two-dimensional array of apertures, in this case conveniently of rectangular form, possibly square, of which one only is shown at 4. The shutters associated with each of the apertures of the array are identical, so that it is necessary to describe one only. The shutter member associated with aperture 4 is generally formed as the whole or a segmental part of a rotationally symmetrical shell, in

this case one half of a cylindrical shell. One circumferential half of the shutter member, the upper half as shown in the drawing, is opaque, while the other half, the half which occupies aperture 4 as shown, is translucent or transparent. Thus when the shutter is in the position shown light, indicated by arrow 71 may pass through aperture 4. When the shutter is in its alternative position, indicated in broken line at 70' the opaque portion of the shutter will occupy aperture 4 to prevent the passage of light therethrough.

Shutter member 70 is pivotally mounted for movement about its own axis 72 and has coupled to it an actuator member 73 which may be a permanent magnet, in which case the actuation of the shutter is effected in a manner substantially similar to that described with reference to FIGS. 2 and 3, or may be a soft-iron member in which case actuation is as described with reference to FIG. 4. In each case the disposition of the energizing conductors 31 and 32 will require to be adapted to accord with the fact that the actuator member pivots about an axis parallel to the plane of the array rather than perpendicular thereto as in the previously described embodiments. The two limbs of conductor 31 lie in a common vertical plane parallel with that of member 2 and spaced to allow actuator member 73 to pass between them. The two limbs of conductor 32 lie in a common horizontal plane which may conveniently be the plane containing the pivot axis, 72 of the actuator and shutter. The shutter and actuator are pivoted upon a pivot pin carried in brackets such as 74 extending from member 2 or otherwise as may be preferred. Stop pins 75 are provided to limit the actuator movement. These may be of magnetic material as previously described.

The magnetic fields produced by conductors '31 and 32 will be understood tobe orthogonal, conductor 31 producing a field of which the lines of force in the vicinity of actuator member 73 extend horizontally, while the field produced by conductor 32 has vertically extending lines of force. As before, the values of the currents passed through the conductors and/or their directions are so chosen that the shutter moves from one stable position'to the other only in response to an appropriate change of current in both of the conductors uniquely associated with the appropriate actuator member.

It will be apparent that the arrangement described above in relation to FIGS. 6 and 7 may be very substantially modified. The shutter member may comprise only that segment of a rotationally summetrical shell which suffices to obstruct the aperture, in which case, as also in the illustrated embodiment, a counterweight 76 may be provided on the shutter to ensure that the intended stable positions are present. It will be understood that if a shutter of other than cylindrical form is used the shape of the aperture must be made to correspond; if a shutter of spherical form is used, for example, the-aperture will be circular.

FIG. 8 illustrates a circuit arrangement for exciting the conductors 31, 31 and 32 32 of a display device asdescribed above when selection of a shutter to be actuated is made by passing currents through the two conductors uniquely associated with that shutter. Electric current from a suitable source 80, represented for convenience as a battery may be passed through any one of conductors 31. Selection of a desired conductor is effected by means of a selector switch 81,

which as shown has been set to select conductor 31 but current does not flow until a control switch 82 is actuated to select the required direction of current. The magnitude of the current passed through the conductor may be set to a required value by means of an adjustable series resistor 83. Current from source may also be passed through any one of conductors 32. Selection of the desired conductor is again made by a selector switch 84 and a control switch 85 prevents current passing through any conductors as the selection is made. Either this switch or switch 82 may be omitted in niany cases, or a known type of selector switch may be used in which a further movement after selection is required to produce a current path through the switch. A resistor 86 may be adjusted to produce a required value of current in the conductors. Obviously, individual current sources suitable to produce the required currents without adjustment may be constructed and employed if preferred. As shown, switches 81 and 84 are set to select conductors 31 and 32 respectively, thus permitting actuation of an actuator with which those two conductors are uniquely associated.

FIG. 9 illustrates a mode of exciting the systems of conductors of a display device as described with reference to FIGS. 1, 2 and 3 when that mode of operation is employed in which each of the horizontal conductors is excited unless a shutter associated with that conductor is to be moved. Vertical conductors 31 are controlledas described with reference to FIG. 8 and the circuit components associated with these conductors are correspondingly numbered and will not be further described. Current from source 80 is also passed through all of conductors 32 by way of individual normallyclos ed switches 87, I and a common adjustable control resistor 86. As shown, switch 87 has been opened to stop the flow of current in conductor 32;, and thus to release all the associated actuators. Switch 81 is set to select conductor 31 so that upon operation of switch 82 to select the appropriate direction of current actuator 90, with which conductors 31 'and 32 are uniquely associated, will be moved. It will be apparent that switching arrangements other than those specifically described with reference to FlGS. 8 and 9 may be used if preferred.

It will be understood that the light transmitting areas in the opaque membersneed not be actual apertures but may be translucent of transparent areas formed in known manner in an otherwise opaque member. When translucent, the light transmissive areas may be c0- loured and the shutter members need not be actually opaque. In some cases they may be translucent but coloured.

Moreover, the light transmissive areas need not be arrangediin rows and columns extending perpendicularly to oneanother, the directions of alinement may be inclined to one another at angles between 90 and 45 if preferred. in such' cases the directions of the fields produced may also depart from perpendicularity.

It should be noted that in all the described embodiments each conductor or conductor limb may be a'single conductor, for low-voltage, high-current operation or may be a multi-turn winding for high-voltage, lowcurrent operation, although only the former construction is specifically illustrated.

It will be understood that while the circuit arrangements described with reference to FIGS. 8 and 9 are devised to permit selection of a single actuator to be moved it will in practice sometimes be Convenient to select several actuators in a row or in a column for simultaneous actuation. In FIG. 8 this may readily be done by replacing one or both of switches 81 and 84 by individual selectively or simultaneously operable switches while in FIG. 9 only switch 81 requires such modification, switches 87 being already operable either selectively or simultaneously.

I claim:

1. In an information display device including a planar opaque member having therein light-transmissive areas arranged in a two-dimensional array of rows and columns and an individual light modifying shutter member associated with each of said areas, each of said shutter members being pivotally mounted for movement between two stable positions in which it has different effects upon light passing through said area, each said shutter member being coupled for actuation between said stable positions by respective actuator member of magnetic material, a first system of magnetic field producing means, each one of said field producing means producing in response to an energizing electric current a respective first magnetic field having a first alignment, each said first field being substantially confined to the actuator members of a respective one of said rows, and a second system of further magnetic field producing means each one of said further field producing means producing in response to an applied electric current a respective second magnetic field having a second alignment, each said second field being substantially confined to the actuator members of a said column and having a direction determined by the direction of said applied electric current;

the improvement wherein each of said systems of magnetic field producing means comprises for each said column of shutter members a single elongate coil including spaced-apart rectilinear conductors each extending parallel to the plane of said array whereby the forces produced on the actuator member coupled to said shutter member as a result of predetermined changes in the magnetic fields produced by the coils of said first and of said second system of which the fields are uniquely associated with said actuator member cause said shutter to be moved from each to the other of said two stable positions.

2. The improvement claimed in claim 1 wherein each said shutter member comprises a laminar member moving between said two stable positions in a plane parallel to that of said array, the coils of said first system of magnetic field producing means comprise conductors lying in a common horizontal plane, with said actuator members of the respective said row mounted for movement in a plane passing between said coil conductors,

and each coil of said second system of magnetic field producing means comprises conductors extending in a respective vertical plane perpendicular to the plane of the array and containing the pivot axes of the actuator members for the shutter members of the respective said column.

3. The improvement claimed in claim 1 wherein each said shutter member comprises at least a portion of a rotationally symmetrical shell mounted for movement between said two stable positions about an axis parallel to the plane of said array, wherein the coils of said first system of magnetic field producing means comprise conductors lying in respective common horizontal planes containing the axes of rotations of said shutter members of the individual said rows and each said coil of said second system of magnetic field producing means comprises conductors extending in respective common vertical planes parallel to the plane of the array and adjacent said shutter axes, with the actuator members of each said column mounted for movement in a plane extending between the conductors of the respectivesaid coil conductors of said second system.

4. The improvement claimed in claim 1 wherein each said actuator member is an elongate permanent magnet, said magnets being all similarly disposed in respect of their polarity in relation to the associated shutter member.

5. The improvement claimed in claim 1 wherein each said actuator member is an elongate member of magnetic material of low coercive force and of low remanence.

6. The improvement claimed in claim 5 wherein each said actuator member is mounted by a pivotal mounting means including a tubular member having a pivot pin member passing therethrough, one at least of said tubular and pin members being arranged to guide the flux of a said magnetic field to said actuator member.

7. The improvement claimed in claim 1 together with means for selectively applying to any of the field producing means associated with either said rows or said columns a respective electric current in either one or the other direction.

8. The improvement claimed in claim 4 together with means for selectively applying an electric current to any of the field producing means in one of said systems and means for applying an electric current to selected ones of the field producing means of the other of said systems.

9. The improvement claimed in claim 1 wherein fixed ferromagnetic members are included in a said field producing means to augment the strength of the magnetic field produced thereby. 

1. In an information display device including a planar opaque member having therein light-transmissive areas arranged in a twodimensional array of rows and columns and an individual light modifying shutter member associated with each of said areas, each of said shutter members being pivotally mounted for movement between two stable positions in which it has different effects upon light passing through said area, each said shutter member being coupled for actuation between said stable positions by respective actuator member of magnetic material, a first system of magnetic field producing means, each one of said field producing means producing in response to an energizing electric current a respective first magnetic field having a first alignment, each said first field being substantially confined to the actuator members of a respective one of said rows, and a second system of further magnetic field producing means each one of said further field producing means producing in response to an applied electric current a respective second magnetic field having a second alignment, each said second field being substantially confined to the actuator members of a said column and having a direction determined by the direction of said applied electric current; the improvement wherein each of said systems of magnetic field producing means comprises for each said column of shutter members a single elongate coil including spaced-apart rectilinear conductors each extending parallel to the plane of said array whereby the forces produced oN the actuator member coupled to said shutter member as a result of predetermined changes in the magnetic fields produced by the coils of said first and of said second system of which the fields are uniquely associated with said actuator member cause said shutter to be moved from each to the other of said two stable positions.
 2. The improvement claimed in claim 1 wherein each said shutter member comprises a laminar member moving between said two stable positions in a plane parallel to that of said array, the coils of said first system of magnetic field producing means comprise conductors lying in a common horizontal plane, with said actuator members of the respective said row mounted for movement in a plane passing between said coil conductors, and each coil of said second system of magnetic field producing means comprises conductors extending in a respective vertical plane perpendicular to the plane of the array and containing the pivot axes of the actuator members for the shutter members of the respective said column.
 3. The improvement claimed in claim 1 wherein each said shutter member comprises at least a portion of a rotationally symmetrical shell mounted for movement between said two stable positions about an axis parallel to the plane of said array, wherein the coils of said first system of magnetic field producing means comprise conductors lying in respective common horizontal planes containing the axes of rotations of said shutter members of the individual said rows and each said coil of said second system of magnetic field producing means comprises conductors extending in respective common vertical planes parallel to the plane of the array and adjacent said shutter axes, with the actuator members of each said column mounted for movement in a plane extending between the conductors of the respective said coil conductors of said second system.
 4. The improvement claimed in claim 1 wherein each said actuator member is an elongate permanent magnet, said magnets being all similarly disposed in respect of their polarity in relation to the associated shutter member.
 5. The improvement claimed in claim 1 wherein each said actuator member is an elongate member of magnetic material of low coercive force and of low remanence.
 6. The improvement claimed in claim 5 wherein each said actuator member is mounted by a pivotal mounting means including a tubular member having a pivot pin member passing therethrough, one at least of said tubular and pin members being arranged to guide the flux of a said magnetic field to said actuator member.
 7. The improvement claimed in claim 1 together with means for selectively applying to any of the field producing means associated with either said rows or said columns a respective electric current in either one or the other direction.
 8. The improvement claimed in claim 4 together with means for selectively applying an electric current to any of the field producing means in one of said systems and means for applying an electric current to selected ones of the field producing means of the other of said systems.
 9. The improvement claimed in claim 1 wherein fixed ferromagnetic members are included in a said field producing means to augment the strength of the magnetic field produced thereby. 